Telephone system



July 31, 1923. 1,463,600

(3. SPARKS TELEPHONE SYSTEM IZZETZE 5z75r2t5.

By 1/ EUZH EZL' Patented July 31, 1923,

.UNHTED STFATES oHAnLns srnnns, or OAK PARK, ILLINOIS, ASSIGNGB TO nuances switrcnnonnn L cence T rarest erricak AND SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

TELEPHONE SYSTEM.

Original application filed August 5, 191.8,Seria1 No. 248,281. Divided and thisapplicationfiled July 9,

sis. Serial nogsoasas.

T 0 all whom?! may concern: 7

Be it known that 1, CHARLES SPARKS, a cit1zen of the Un1ted States of America,

residing in Oak Park, county of Cook, and

State of Illinois, have invented certain new and useful Improvements in Telephone Syste1ns,,of which the following is a specification. I

L y invention relates to telephone systems and has to do more particularly with sys may cause a cessation of the operation of said signaling apparatus by signaling for disconnection.

Another feature of my invention is the provision of means in a universal link circuit whereby whenthe link circuit is in use to establish connection between a calling and a called-line, and the called line is being automatically signaled, the ringing apparatus may be rendered quiescent by a control exercised at either the calling or the called substation. The present application is a division of my application for Letters Patent, Serial Number 248,281, filed August 5,1918; t.

'These as well as other features of my invention will be more particularly pointed out in the ensuing specification and in the appended claims.

For a better understanding of my invention, reference may be had to the accompanyingdrawing which illustrates my invention operating in connection with a universal cord circuit used for establishing connection between lines of different character, such as common battery and local battery lines. 7'

Referring now more particularly to the drawing, I show a universal cord circuit C adapted to interconnect telephone lines of difierent' character, for example: to connect common battery and local battery telephone I lines; common battery and common battery lines, or local battery and local battery,

lines. To the left of the drawing, I Show a calling common battery subs-tationAand a calling local battery substation l3, and" to the right of the drawing Ishow a called common battery substation D and a called;

local battery substation E. The common battery substations A and D terminate respectively at the exchange in line circuits L and L, with the usual line relays LR and LR, cut-off relays C0 and CO, line signals,

5: and S, andmultiple jacks J and J. The local battery substations B and E terminate L and L which line circuits comprisethe respectively at the exchange in linecircuits I high resistance wound cut-oft relays .CO H

and CO multiple jacks J and J and drop signals DS and DS.. Y

an answering plug APand'a calling plug til the two plugs being connected by thew heavily marked conductors and through the.

of the cord circuit C comprises a switching relay SJV, which relay energizes when the plug AP is inserted into the jack of a com-.

mon battery line, the said relay SW remaining at normal when the plug AP 1s inserted into thejack ot a local battery line, due'to' the high resistance ofthe winding of the cut-oil relay of the local battery line circuit.

A supervisory relay is provided which is actuated over theline when a connection is'made with a common battery ll11G.;: A

disconnect relay DRis also provided which is actuated when a local battery subscriber transmits a d1sconnect signal to the exchange by the operation of his hand generator, An answering supervisory lamp vAL- s also associated with theanswering end. o'tthe cord circuit C for the usual supervisory purposes. The calling end of the cord'cir'cuit Goontains similar apparatus tothat described in connection with the answering end of the cord circuit C, namely, a switching relay Sll .a supervisory relay SR, anda disconnect relay DR, In addition I provide :a party line ringing key Eli for connecting one of a plurality of ringing generators G, G, G and G tosignal the subscriber at a called for substation. A ringing control relay is also provided, which relay is ener ized upon the actuation of the ringing key K to connect ringing current to the called line and remain e g zed. un il the A H r 70 The universal cord'circuit Q comprises called subscriber answers in response to the signal. An interrupter relay IR is also provided which is energized upon the actuatlon of the ringing key BK to connect ringing current tothe called line to give an instantaneous first ring to the called for sul scriber. The're lay RC also connects the interrupterl to the interrupter relay IE to intermittently energize and de-energize the relay IR to intermittently connect ringing current to the called line. To signal a local battery substation the operator must depress one of the ringing plungers to connect our-rent to the called line each time the sub LK is provided for connecting q-tors set 10 to the conductors to inquire the i sor'i be' it more in detail operat drawing and assuming that the Cu establishes an energizing circuit for relay LR, which relay, upon brings about the lighting of the lin station bell is to be operated. Acalling .supervisory lamp usual supervisory purposes. A listening key the operawants of the ubscribers. 1 also provide an interrupter l for flashing the supervisory signalsall. and CL when disconnection is desired, aswil-l be more filly hcroinaiter described. I r

Having described in general the arrangement of the circuits employed in my'inyention, l w

nection with the exchange .tr'ated. I

Referring now more particula tery subscriber at substation A ini 'call,'=the removal of the receiver thcr the line tion,

the cord circuit C, the said circuit being V traced from battery through the winding of the switching relay SW, over conductor 5 through sleeve contacts of the connected plug AP and jack J, and through the frieding of the cut-ofi 'relay CO to ground. The cutoff relay C(Lupon energizing, opens the circuit of the relay LR, which relay restores and efiaccs-the line switch S. The closing or" alternate contacts 6 and '7 of the "switching relay SW establishes an energiz ing circuit for the supervisory relay SR,- trac'ed from battery through the lower winding '8 of relay: SR, conductor 9, alternate contact 7 of relay Sil conductor 10, cor.-

duc'tor ll,'winding 2023 the repeating coil RP, ring contacts'ot the connected plug AP and jack J, through the now closed'contacts of the substations itch hook, back over-the tip contacts of the connected jack 5 and j'ilug AP, winding 1 of the repeating o QL is also provided for the subscriber answers.

es I '1,4=63,600

RP, conductor alternate contact lay SW, and through the WLHCllDg 1; ot the supervisory relay SE to ground, ;.'l-he-opening of normal contact 1 of the supervisory relay SR prevents the premature lighting of the answering supervisory lainp All.

Common cattery'to coni /a007 battery.

The operator now inquires the wantsof the calling subscriber at the common bat-V tery substation A, and assuming that it is the subscriber at thelcoinnion' battery substation E- that is wanted, the operator tests the multiple jack .l" of the called line-in the usual manner, and assuming that line is idle she inserts calling plu GP into the jack 5 of the calledl'ine this insertion of plug l? into jack J closes a series ener izing circuit for the cut-off relay C of the line circuit L and the switclr i g relay cllV from battery through the winding of the switching relay Sil conductor 15, sleeve contacts of the connected plug GP and aclr J, and through the winding of thecut-ofi' relay Lil to ground. The closingof natecontacts 16 'andlT of the switch ng re "lay Sil establishes an energizing circuit for the calling supervisory lamp CL, traced from battery through'the alternate contact- ;l'l', conductor ll, through the lamp CL 'conductor 1, normal contact 20 oi the ringing control relay 1C, conductor 21', alterg nate contact- 16 of the relay SW conductor 22 to ground at normal contact28 of super visory relay SR4, the'said supervisory lamp CL remaining lighted until the joperator actuates the ringing key Eli. The closing of alternate cori'tacts' supervisory relay 8? to the cord conductors, but due to the open switch hoo k'coir tacts at the called substation B, the said the and 25 connects the of the cord circuit Q, traced V relay SR remains at nornial untilthe called ringing key plunger of the ringing key-BK to its fully depressed position, which moves the end s rin 's 26 and 27 of the rin 'ine' ke' 7- 1 a :7 s v :3 D

Rh to their alternate position, and. connects the arc aer 1111 111 generator G G G or G to signal .the called ior subscriber at substation B. The closing of alternate contact 26 of the'end sprlngs establishes an energizing circuit for the ringing control relay RC; traced from battery through the winding of the said relay RC, conductor 23., alternate contact 29 of relay SlV,;c0nduC- tor 30,alternate contact :31 of relay SR,

conductor '32., conductor 33; conductorfli alternate contact 26 of the end springsycon-- ductor 35 and conductor 22,' to ground at normal contact 23 of relay SR.

upon energizing; then closes a locking circuit itself; traced from battery The relay 7 throughthe Winding of relay RC, conductor 28, alternate contact 29 of relay SW,

conductor 30, alternate contact 31 o't'relay SW, conductors 32 and 33, alternate contact 20 of the ringing control relay RC, conductor 21, alternate contact 16 of relay SW, and conductor 22 to ground at normal contact 23 of relay SR. The interrupter relay IR which wewill assume is the selected ringing generator. to the called line from the ungrounded pole or" the generator G, alternate contact 41 of the ringing key plunger, conductor 42, alternate contact of relay IR, tip contacts of the connected plug (Y? and jack J, through the condenser and call bell of the called substation D, back through the ring contacts of the connected plug Cl? and jack J, to ground at alternatecontact 43 of relay IR. This connection of ringing current,'immediately upon the depression of a ringing key plunger of ring key BK,

gives an instantaneous first ring of the called subscribers callbell. The opening of normal contact 20 of relay RC eliaces the calling supervisory signal CL. The closing of alternate contact 44 of relay RC connects the interrupter I to the lower winding 45 ot' the interrupter relay IR, the circuit being traced from battery through the winding 4510f relay IR, alternate contact 44 ot relay RC, conductor 46, through alternate contact 47 of relay Sl/V, and through the constantly rotating interrupter I to ground. The relay IR is thus intermittently energized and de-energized 'to' connect ringingcurrent from the generator G to the called line over a circuit traced from the ungrounded pole 01" the generator G, through alternate contact 41 of the ringing key plunger contact, conductor 42, alternate contact 40 of relay IR, tip contacts of the connected plug CP and jack J, through the condenser and call bell at the called subscribers substation fD,'back through ring contacts of the con nected jack J and plug CF, to ground at alternate contact 43 of relay IR. The closing of alternate contact 48 of relay TR transmits an audible tone to the calling subsc iber at the substation'A, traced over a 'circuitextending from the ungroundedpole of the generator G over conductor 49, through resistance 50, condenser 51, alternate contact 48 of relay IR, conductor 52, tip conductor of the cord circuit C, winding 3 of the repeating coil RP, conductor 53, alternate contact 24 or" relay 3V7, through the upper contact 117 of the relay SW1.

winding of relay SR to ground. The ringing tone is induced'in the other Winding of the repeating coil RP and transmitted to the calling subscriber at' substation A, giving the subscriber thereat an audible signal notifying him that the called subscriber is being signaled. The called subscriber at substation D is thus automatically signaled until the subscriber thereat answers in response to his call signal oruntil the calling subscriber replaces his receiver. Should the calling subscriber replace his receiver be- "fore the called subscriber at substation D answers, the replacing'of the receiver thereat opens the circuit of the supervisory relay SE at the switch hook contacts, and the re- SR, upon de-energizing, opens its alter- 'from'thewinding 45 of the relay'IR, which nate contact 31 to open the locking circuit of the ringing controlrelay EC. The relay relay de-energizes'and opens its alternate contact 40, thus preventing further application of ringing current. The relay'SR restor inn; closes its normal contact 14, closing a circuit for the answering supervisory lamp AL, traced from ground at normal contact 14, over conductor 54, through alternate contact 55 of relay SW, through the lamp AL, and

conductor56 to battery and ground at alter-f nate contact 57 of relay SW. The closing of normal contact 20 of relay RC, upon its restoration, closes a circuit for the. calling supervisory 'lampoCL, traced from ground at normal contact 23 of relay SR, conductor 22, alternatefcont-act 16 of relay SW, conductor 21, normal contact 2Q of relay RC, conductor 19,.through the lamp CL, and con ductor 1S to'battery and ground at alternate The operator noting the two lighted signals AL and CL knows that both the calling subscriber and the called subscriber have replaced their receivers on the switchhooks, and now withdraws the answering and calling plugs AP and CP from their respective jacks. J and J, opening'the series ci'rcuits for the relays CO and SW, and CO and SW. The relays i SW and SW restoring, place the apparatus.

ot'the cord circuit Catnormal, and the said cord is now available for establishingother connections.

The subscriber at the in response to his call signal, removes his, recelver from 1ts sw1tch hook, and when the relay 1B is in one of its deeenergized positions an energizing circuit for the supervisory relay SR s established, traced from battery throughth e lower winding 58 of relav SR, over conductor 59, through altercalled substation D nate contact 25 of relay SW, conductor 60, V

conductor 61, winding 4 of the repeating coil normal contact 43 of relay IR, ring contacts o-f the connected plug 'CP and jack J,

through the now closed contacts of the substation switch hook, back. through the tip contacts of the connected jack J and plug TCP normal contact eO'of relay IR, winding oftrc repeating coil conductor 53,

alternate contact 2i of relay SW, and

through the yin-ding 62 of the supervisory relay to ground. I r

' The opening 01 normal contact 22 of the supervisory relay SE" opens the loclnng'cir- EC rest-ores opening its alterallows relay IE to remain at norof the relay it prevents further application current from the generator G- to the called subscriber who has now an swered h s call in response to his call signal. The calling and called SUlJSCIlbETSfii] the substations A and D are now in COIIVQFSQUOIIal circuit, the talking circuit being traced over the heavily inarkecl conductors.

After the subscribers have finished conversation, they replace their receivers upon their respective switch hooks, causing the supervisory relays SR and SF. to. restore. The restorationof the supcrsisory'relay SR causes its'norinal contact 14 to close, establishing an energizing circuit for the ansupervisory larnp AL, traced from ground at normal contact l l,-'o,ver conductor through:alternate contact 55 or relay 3W, throughthe lamp AL, and conductor to battery and ground at alternate con- 7 of relay SiV. The restoration of the to close, establishing an energizing ciituit-itor the calling supervisory lamp CL,

of re lay EW, over conductor 18, through mp CL, conductor 19, normal contact I 20:01" relay RC, conductor 21, alternate con- 45 tact l6 oi. relay fill, and conductor 22 to ground at normal contact 28 of relay SE. The operator noting the two lighted signals knows that the subscribers have replaced their receivers and withdraws the answering and'calling plugs A and CE from their respective :jaclts J and J, allowing the switching relays SW and SW to restore,

placing the apparatus of cord circuit C at.

normal ready for establishing other connections The cut-.oil-relays CO and C0 also restore to normal when the plugs AP and GP are withdrawn, placingthe line circuits Lend L at norrnal.

Local Zmz'tcry to local battery. Assuming; now that the local battery sub station 13 initiates a call, the actuation of the hand generator by thesubscriber brings about the operation of the drop signal D8, and the operator noting the actuated drop n' in control rela RC and contact 44, disconnecting. the inter? from the winding 45 of the relay o opening of alternate contact 40 rvisory relayrSR causes its normal contraced from battery at alternate contact 1? i tend sp rings 26 and 27.

-1,4oe,eoo

signal DS inserts the answering plug AF or" cord circuit C into the gao'l; J of the calling line. The nsertion of the plug AP 1nto' the eel; w restores the drop signal DS and establishes a series ener fizir circuit for the cut-off relay C9 and the sWitching re-E lay SW of the cord circuit C. This circuit is traced from battery through the Windingof relay SlV, over conductor 5, through sleeve contacts of the connected plug AP and jack J and through the winding of the high resistance cut-off relay CO to ground. The cut-off relay CO energizes, but due to the high resistance of the said cut-oil r -av C6 of the local battery line circuit L ins at normal. The operator now actuates h the local battery substation iissunn ing that it is the local battery substation E that is wanted, the operator tests the line in the usual nianner, and finding it idle, the operator inserts the calling plug (JP into, the ,aclz- J of the wanted line; A series circuit is e lishecl ior'the cut-off relay CO of the local battery line circuit L andthe switching relay Sl V of the cord circuit C, traced from battery through-the winding of the relay S il over conductor-l5, through ring rontacts of the connected plug CPand jaclr J and through the winding 'ofthe redoes not operate, due to the Vhigh reto ground at normal contact 23 of relay SE. .Theclosing- 0i alternate contact 39 ofirela EC establishes an eneroizin cirn b cuit for the interrupter relay 1P2, traced from battery through the winding 36 of relay IR, conductor '37, alternatecontact 27,

and conductor 38, to ground at" alternate contact'39. lhe closing of alternate contact 4-0 of relay IR connects ringing current from generator G, through alternate contact 41 of the ClGPI'QSSQd' key, plunger of ringing key BK, conductor 42, alternatecontact 40 of relay IR, tip contacts of the plug GP and jack 3, throng-lithe call bell otthe called substation E, back through the switching relay Sil fails to operate and er listening key LK to connect heroperators set C to the cord conductors and nquire-s the wants of ti e calling subscriber ance of relay CO and remains atnor but. therelayCO energizes.- The oper- 3G to ground; The switching relay of the jack J and plug CP, alternate contact 43 ot relay no locking circuit establ shed ring 'contacts to ground at IR. There is for the relay RC, due to the switching re lay SlV' remaining at normal, and,for each applicationor" ringing current the operator must depressthe ringing key plunger. The

locking circuit of the relay RC extends through alternate contacts the switching relay Sil and as the switching relaySW is at normal during the connection of the calling end of thecord circuit C to the lo cal battery line E, the relay RC does not lock up." llelay SW remaining at normal also prevents the interrupter I from being connected with the interrupter relay IR.

The operator thus rings the call bell at the tive switch hooks and actuate their hand generators tosignal the operator of the cord circuit C, The subscriber at substation l3 having actuated his hand gener curreir will pass through the disconneci' elay- Dir of the cord circuit C over a circuit traced from the hand generator at the substation B, over the tip side of the line, through the tip contacts of the jack J 2 and plug rL, winding 1 of the repeating eoilliP, conductor 12, normal contact 6 of relay SW, conductor 63, through the winding of the disconnect relay DR, conductor 11, winding '2 oi the repeating coil'RP, ring contacts of the plug AP and jack J and back to the generator atthe substation l3. l l hcn current passes through the disconnect relay, it is energized and closes itsalternate contact 64, bringing about the energize.- tion of the supervisory relay SR, over a c cuit traced from battery through the wind ingS of the relay SR, conductor 9, normal contact 7 of switching relay SW conduct-on resistance 66. normal contact 67 or listening key LK, and conductor 68 to ground at alternate contact (35% or the relay DB. The relay SR, upon energ1z1ng,'closes a locking circuit for itself, traced from battery through the windings oi the relay SR, conductor. 9, normal contact 7 of relay SW conductor 65, resistance 66, normal contact 67 and conductor 68, to ground at alternatefcontact 14: of relay'Sld. When the subscriber at the calling substationB has ceased actuating his hand generator, re-

lay DR restores'to normal and-closes a'circuit for the answering supervisory lamp AL, traced fromzground at alternate con- 'tact 14: of relay SR, through normal contact 64 of, relay DR, over conductor 69, through normal contact 55 of relay SW, conductor 56, normal contact 57, conductor 70, andithrough the constantly rotating interrupter I to battery and ground. supervisory lamp AL is thus flashed, due to the interrupter I, giving the operator of the cord circuit. C a flashingdisconnect signal, or if the code signals have been ar-, ranged, the subscriber at the substation may actuate his hand generator according to a predetermined code and notify the operator of the cord circuit C, whether the a disconnect signal,

flashing signal is cit er or a recall signal. During the actua ion of vthe hand generator at the calling substation 13, the current, passes through the re lay DR and is thus held energiZed and its normal contact 64 remains open during this period, preventing the interrupter circuit through the lamp AL from being closed.

' Thus: the flashing is started only after the currentfro'm the hand generator through the relay DR has ceased The operator noting the flashing signal actuatesher listen ing key L12, should the flashing signal be a recall, and interrupts, the normal contact 67,

of listening key LK, thereby opening the locking circuit of'the relay SR, which re lay (l6-GI1GlglZ6S and opens its alternate con-v ll, interrupting the flashing circuitof The,

the lamp lrl to preventjfurther flashing of the signa The subscriber at the local battery substa; tron E now actuates his hand generator after,

finishing conversation, and the vcurrent from his handgenerator actuatesf the disconnect relay DR, as is apparent from the previous description in connection with relay DR. The closing of alternate contact 71 of the/ relay DR establishes an energizing circuit for the supervisory relay SR traced from battery through the lower winding 58 of relay SH, conductor 59, normal contact 25 of relay SW, conductor 72, resistance'73, normal contact T45 of listening key LK, and con- 7 ductor75 to ground at'alternate contact 71 of relay DE. The relay SR now closes a locking circuit for-itself traced troni'battery vented from flashing for the'reasoh previousiy described in connection with the supervisory lamp AL. 'l Jhen the subscribers at the substation E has finished sendlng; a V

disconnect signal, the relay DR restores to normal, and the closing ofnormal contact 1 closes a circultfor the calling supervisory lamp CL, traced from ground at alternate 1 contact 23 of relay SB", through normal contactv 71 of relay DRQconductor 76,1101:-

a 21, normal contact 20 of relay RC, conductor 19, through the lampv CL, conductor 18, nornial contact 17 of relay SW, conductor 79, and through the interrupter l to battery and ground. The calling supervisory lamp CL is-caused to flash due to the constantly rotating interrupter l to give the operator a fiashingdisconnect signal, or in case of a code signal to" signal the operator for recall, The operator noting the two flashing disconnect signals of lamps All and CL knows the'conversa-tion has terminated and now actuates her listening LK to interrupt contacts 67 and 7 1 to open the locking circuits relays SR and SEQ-allowing the relays to restore. a The opening of alternate contacts 14 and 23 01" relays SR and SR opens the circuit of the flashin supervisory signals AL and (IL, and thus prevents further flashing of the signals. The operator now withdraws the answering and calling plugs A]? and GP from their respective jacks J' andfJ allowing the relays CO and C6 torestore. The apparatus of cord circuit C and line circuits L? and L? are now at normal and available for establishing other connectio s 1 i vfhenjalooal battery line is signaled, the discharge of the line might bring up the relay DR and close a circuit for'the relay SR", which would lock up and cause the sig nal CL to flash and give a false disconnect if some means Were not provided to guard against this. To overcome this, I provide a short circuit for the'relay DR, as will now be described. After each application of ringing current, a discharge from the line is sent back thr ugh the tip of the plug, through normal contact 40, through winding 391 the repeating coil'RP, over conductor 53,1 1ormalcontact 24 of relay SW over conductor 80, through alternate contact 81 of relay RC, whichrelay being slow to release holds up momentarily after each application'of ringing current, over conductor 82,

through normal contact 83 of relay IR, to

cthe ring conductor of the cord circuit C.

Thisipath for the line discharge places a short'circuit about the disconnect relay DR and, prevents the line discharge from affectthe relay D3,, The relay DR thus remains n rmaLQthereby preventingthe giv;

ing of a false disconnect signal. Oommmtbcz/crg to local battery.

Should a calling common battery subscriberat' the substation .A wish to converse with the local. battery subscriber at the substation E, the insertionof the plug AP into the jack J brings about the energization of the switching relay SW and the cut-ofi' relay CO, and theclosing of alternate confacts 6 and 7 of relay Sl/V brings about the actuation of the supervisory relay same:

the line. The operator in inserting the calling plug GP into the jack J of the local bat-. tery line E brings about the energization of the relay 00 through the switching relay SW, but the switching relay SVV' does not disconnect signal, when the local battery subscriber at substation Esends a disconnect signal, is readily apparent from theprevious description.

The subscriber at the local battery substation 3 when calling actuates l11S drop s1gnal DS, and the operator in responsethereto I inserts the answering plug 'AP into the jack J In this instance, the cut-cit relay CO actuates, but the switching relay-S w does not operate for reasons as alrea-dy de scribed. The common battery subscriber at substation D being wanted, the operator inserts the plug CP in the jack J of the called line and closes a series circuit for relays SlV and GO", both relays operating. Theoperator now'depresses the proper ringing key plunger to bring about the actuation of relay RC and connect ringingicurrent to the called line. The circuit forrelay RC is traced in this instance from battery through the winding of the relay RC, conductor 28, normal contact 29, conductor 33, conductor 34-, alternate contact 526, and conductor 35 to ground at normal contact 23 of relay. SR.

The relay RC has a locking circuit estab 105 lished through its alternate contact 20 and contact 29 ofrelay SW, and from this point. on the operation is the same as previously described, includin the disconnect signal of the calling local battery subSGriber atsubstation B, and that of the common battery subscriber at substation D.

' While I have illustrated only oneforin goj of my invention, I do not wish to. be limited V to the same as various other arrangements may readily suggest thernselves tothose slrilled in the art, and I, therefore, aim to cover all such changesjand modifications as come within the spirit scope of the appended claims.

' VVhatI claim as new and desire to secure by United States Letters Patent, is}

'1. A telephone system including comnaon' battery and local battery telephone lines, a

universal cord circuit for interconnecting sa1dl nes, automatic ringing means includ. mg a double wound relay for said cord; c.1r-'

cuit for ringing a called one of said telephone lines, said double wound relaycontrolling contacts in the talkingconductors of said cord circuit and operable intermittently to apply ringing current to the called line to intermittently signal the called sub scriber on said called line, a supervisory relay for said cord circuit controlled over the calling one of said telephone lines, and a controlling circuit for said automatic ringing means controlled by said supervisory relay so that when the said calling subscriber signals for disconnection the said automatic ringing means is disassociated from said called line.

2. A telephone system including common battery and local battery telephone lines, a universal cord circuit for connecting said lines, automatic ringing means including a double-wound ringing relay for ringing a called one of said subscribers lines, an operator-controlled key, and means controlled by said key for closing a circuit through one winding of said relay and for connecting an interrupter in circuit with the other of said windings.

3. A telephone system including common battery and local battery telephone lines, a universal cord circuit for connecting said lines, automatic ringing means including a double-wound ringing relay for ringing a called one of said subscribers lines, an operator-controlled key, means controlled by said key for closing a circuit through one winding of said relay and for connecting an interrupter in circuit with the other of said windings to intermittently signal said subscriber, and means controlled by a calling one of said lines for disassociating said ringing means from said'line.

4. A, telephone system including common battery and local battery subscribers telephone lines, a universal link circuit for interconnecting said lines, ringing means for said universal link circuit, differentiating means in said universal link circuit operable when the link circuit is used to connect subscribers lines of one class to connect means to automatically intermittently signal a called subscriber and to manually signal a called subscriber when used to connect lines of a different class, operatoncontrolled means for initiating the operation of said ringing apparatus to intermittently signal the said first called line, and means for interrupting the application of ringing current by a control exercised by both the calling and called substations.

5.- A telephone system comprising local battery and common battery subscribers telephone lines, a universal link circuit for interconnecting said lines, means including a double-wound intermittently operable relay for intermittently applying ringing current to a called one of said lines, operator'- controlled means for initiating the operation of said ringing means, said doublewound relay controlling contacts in the talking conductors of said link circuit, a relay controlled over the connected-with calling line for disconnecting the ringing current from the called subscribers line, and a relay controlled over the called subscribers line for disconnecting the ringing current from the called line. I I

6. A telephone system including common battery and local battery subscribers telephone lines, a universal link circuit for use in interconnecting said telephone lines, automatic ringing means including a double- Wound intermittently operable relay primarily controlled manually for said link circuit for intermittently applying ringing current to a called one or said lines When said link circuit is used to connect lines of one of said classes, a relay controlled over another one of said lines for interrupting and preventing further application of ringing current to the first of said lines, and a circuit controlled by said double-wound'relay for extending a revertive ringing tone to the calling subscribers line when ringing current is being applied to the called subscribers line to apprise the calling sub-' scriber of such fact. 7 a

7. A telephone system including common battery and local battery subscribers lines, a universal link circuit for interconnecting said lines, a source of ringing current,

operator-controlled means including a double-Wound intermittently operable relay, a ringing control relay controlling both Windings of said relay for connecting intermittently said ringing current to a called one of said lines, a relay controlled over a calling one of said lines, means controlled by said relay for preventing a further application of ringing current to the said called subscribers line, and a circuit controlled by said double-wound relay for extending a revertive ringing tone to the calling subscribers line When ringing current is being applied to said called line to apprise the calling subscriber of such fact. a

8. A telephone system including common battery and local battery subscribers telephone lines, an operators universal link circuit for use in connecting said lines, a source I of ringing current, a relay adapted to be operated intermittently to connect said ringing current to a called subscribers line, a ringing control relay controlling the operation of said first relay, means for operating said ringing control relay to initiate the operation of said first relay, and electromagnetic means controlled by a calling subscriber for de-energizing said ringing control relay to prevent further operation of said first relay, thereby preventing further intermittent,applications of ringing current to the said called subscribers line.

9. A'telephone system including common 7 battery and local battery subscribers telephone lines, an operators universal circuit for interconnecting said lines, a source of; ringing current a relay adapted to be operated intermittently to connect said ringing current to a called one of said subscribers lines when said link circuit is used to connect lines of one of said classes, electromagnetic .devices ton controlling the operation of said relay, means for operating one of said electromagnetic devices to initiate theoperation of said relay, and means controlled over .the calling subscribers line for effecting the operation of one of said electromagnetic devices to prevent further operation of said relay, thereby preventing further. application of ringing current to the said called subscribers line.-

10. A telephone system including common battery and local battery subscribers telephone lines, an operators universal link circuit for. interconnecting said. lines, a source. of ringing current, a relay adapted to be. operatedintermittently to connect said ring.

the operation 01 one of said electromagnetic devices to prevent further operation of said relay, thereby preventing turther applica tion of ringing current to the said calledsub scribers line, and other means controlled over said called subscribers line for preventing turther actuation of said relay if said called subscriber responds prior to. the

said calling subscriber exercising control over said relay.

Signed by me at chicago in the county.

of Cool: and State of Illinois, this 7th day of July, 1919.

CHARLES SPARKS. 

